Forest Ecology and Management, 32 (1990) 167-172 167 Elsevier Science Publishers B.V., Amsterdam-- Printed in The Netherlands Estimation of the Aerial Biomass of Weedy Shrubs by Regression Methods: Studies on Adhatoda vasica ARVINDSINGH I$, MIRAMADAN' and PADMA VASUDEVAN ''a ICentre [or Rural Developmentand Appropriate Technology, Indian Institute o[ Technology, Hauz Khas, New Delhi-llO 016 (India) (Accepted 20 December1988) ABSTRACT Singh, A., Madan, M. and Vasudevan,P., 1990. Estimation of the aerial biomassof weedy shrubs by regressionmethods: Studies on Adhatoda vasica. For. Ecol. Manage., 32: 167-172. Estimation of above-groundbiomass ofAdhatoda vasica on a fresh-weight basis has been done, using observedweight (Wo) as dependentvariableand basal radius (p) of stem just aboveground and height (H) of plant as independent variables, through linear regression techniques. Basal radius indicated an almost linear relationship with weight, while height appeared to be a redun- dant factor. The best estimates were obtained using the equation Wo = bp2× H + C, though rea- sonablyaccurateestimation can be done also through equation Wo = bp + C, whereC is the regres- sion constant. Adhatoda exhibitedfairlyuniformdistributionof moisturecontent alongthe height. INTRODUCTION A good variety of neglected or little-known plants including weeds can be prospective sources of biomass for food, fuel, fodder, fertilizer, fibre, etc. (Va- sudevan et al., 1984; Gilreath, 1986; Singh et al., 1987). Multiple use of weeds requires an improved understanding of their biomass productivity. Many methods for estimating biomass production and distribution have been dis- cussed for major forest types, trees, separate component of the trees, shrubs, etc. (Young et al., 1964; Satoo, 1966; Singh and Sharma, 1976; Parde, 1980; Auclair and Cabonettes, 1982), but only a few for under-exploited plants (Va- sudevan et al., 1986). Dimensional analysis, with equations and regressions as necessary requisites, is the most commonly used method for estimating above- ground biomass, and such estimation are reasonably accurate (Ribe, 1979). 2present address: Dept. of Botany, C.M. Science College,Darbhanga-846 004, India. 3Authorto whomcorrespondenceshould be addressed. 0378-1127/90/$03.50 © 1990 Elsevier Science Publishers B.V.